1. Field of the Invention
The present invention relates to a method for fabricating an Active Matrix Organic Light Emitting Diode (AMOLED) display device and a structure of such device, and particularly to a method for fabricating an AMOLED display device and a structure thereof, in which color filter layers are processed by a half-tone mask.
2. Description of Related Art
An Organic Light Emitting Diode (OLED) is a semiconductor device capable of efficiently converting electrical energy into optical energy. OLEDs are wildly used as luminous elements in indication lights, display panels and optical reading/writing heads. Wherein, OLED display devices, having advantages such as free-viewing angles, simple processing, low production cost, fast response, wide operation temperature range and full color displaying, meet the demands of modern display devices in the multimedia field. So, in recent years, OLEDs are being enthusiastically researched and developed.
An AMOLED display device having a structure of color filter on array (COA) has been proposed. The fabricating methods and structures related to the AMOLED are also developed and proposed by many scholars. FIGS. 1A through 1F are schematic cross-sectional views illustrating a process for fabricating a conventional AMOLED display device having a structure of COA.
Referring to FIG. 1A, a substrate 100 is prepared. The substrate 100 has a device layer 110 configured thereon. The device layer 110 includes a plurality of thin film transistors (TFT) 120 (only one exemplarily shown), a plurality of scan lines (not shown) and a plurality of data lines (not shown). The TFTs 120 are driven by the scan lines and the data lines.
Referring to FIG. 1A, each TFT 120 includes a silicon island 121, a gate-insulating layer 122, a gate electrode 123, a source electrode 124a, a drain electrode 124b, an inter-layer dielectric (ILD) layer 125, and a source/drain contact metal 126. The ILD layer 125 has an opening 125a configured for exposing the source electrode 124a and the drain electrode 124b of the TFT 120. The source/drain contact metal 126 is electrically connected with the source electrode 124a and the drain electrode 124b. The source/drain contact metal 126 is adapted for electrically connecting the TFT 120 with a sequentially formed transparent conductive layer 150.
Referring to FIG. 1B, the ILD layer 125 is taken as a buffer layer for making a color filter array, that is the foregoing mentioned COA structure. Three times of procedures including coating color light resistant, exposing and photolithography are processed for respectively forming a red color filter layer 130, a green color filter layer (not shown) and a blue color filter layer (not shown) on the ILD layer 125. It is to be noted that the positions of the red color filter layer 130, the green color filter layer and the blue color filter layer are respectively corresponding to the subsequently formed pixel areas 162.
Now referring to FIG. 1C, a flat layer 140 is then formed on the substrate 100. The flat layer 140 covers the red color filter layer 130, the green color filter layer (not shown) and the blue color filter layer (not shown). Then, the flat layer 140 is patterned for forming a contact window opening 142, which exposes the source/drain contact metal 126.
Referring to FIG. 1D, a transparent conductive layer 150 is formed on the flat layer 140. The transparent conductive layer 150 is electrically connected with the source/drain contact metal 126 via the contact window opening 142.
Referring to FIG. 1E, a pixel defining layer 160 is then formed on the transparent conductive layer 150, for defining a plurality of pixel areas. The pixel defining layer 160 is generally formed by either coating an organic photoresistant layer, followed by exposure and photolithography; or coating an inorganic layer and then processing procedures of photolithography and etching.
Then referring to FIG. 1F, an organic light emitting layer 170 is formed in the pixel area 162 and thus completing the fabrication of the AMOLED display device 200. The organic light emitting layer 170 is controlled to emit light by switching actions of the TFT 120 to apply voltages on the transparent conductive layer 150. Light emitted from the organic light emitting layer 170 is therefore filtered by the color filter array layer (as the red color filter layer 130 shown in the drawings) to be color light.
It is to be noted that the process for fabricating the color filter array layer of the foregoing AMOLED display device 200 having COA structure requires three times of procedures including coating color photoresistant layer, exposing and photolithography. Further, a process of patterning the flat layer 140 to configure the contact window opening 142 is needed for electrically connecting the TFT 120 with the transparent conductive layer 150. Furthermore, another procedure including coating and patterning processes is also needed for configuring a pixel defining layer 170, which is required for defining the pixel areas 162, in which the organic light emitting layers 170 are to be coated.
According to the foregoing, the fabrication of the conventional AMOLED display device 200 having COA structure is complicated and the production cost thereof is unlikely to be lowered.